This invention relates to the flotation of barite from gangue contained in barite ores and is particularly directed to a novel frothing and collecting composition and admixtures of the active component of this novel composition with previously used barite collectors, which admixtures are efficient in carrying out the flotation of barite.
The old and well-known process of beneficiating ores by means of froth flotation has been applied to the beneficiation of numerous ores. Briefly, in a froth flotation process, an ore is finely ground, the resulting fine material is suspended in water to form a fluid pulp, the entire mass is agitated and aerated in the presence of a collector and a frothing agent to form a froth floating on the surface of the liquid, and the froth, containing a high concentration of a desired mineral, is skimmed off.
In this process, the collector, a chemical, must attach itself to the surface of the desired heavy mineral particles, thus giving the mineral particles a hydrocarbon-like surface layer, usually of monomolecular thickness, which is capable of adhering to air bubbles. The air bubbles carry the heavy mineral upward into the froth where it may be skimmed off by any suitable skimming device.
Obviously, the collector used for the beneficiation of any particular ore must be highly selective, so as to form films exclusively upon the surface of the desired mineral and not upon the gangue. This selectively allows floating of only the desired mineral particles, whereas the undesired gangue remains in the tailings.
Barite, or native barium sulfate, BaSO.sub.4, is an important mineral with wide industrial applications. Because many of the higher grade deposits of barite in the United States have been worked out, miners of this material have been forced to obtain increasing amounts of barite from lower grade ore bodies, including tailing ponds, wherein the barite is present with gangue minerals such as limestone and various silicious minerals such as quartz, clay minerals, feldspar and the like. As a result, froth flotation for the beneficiation of barite is becoming increasingly more necessary.
One of the principal uses of barite floated from gangue minerals is as a weighting material for drilling mud used in the drilling of oil and gas wells. However, a mineral containing a hydrophobic coating is not well-suited for use in an aqueous drilling fluid. Rather, in a drilling fluid, a hydrophilic surface is desirable for deflocculation and proper dispersal of the weighting material products, as well as for avoiding foaming when the weighting material is added to a typical drilling mud. Preferably, therefore, a flotation reagent, to the extent it forms a hydrophobic coating, should be easily removed from the beneficiated mineral.
It is desirable moreover, that the temperature at which removal is effected be low enough to avoid an excessive proportion of soluble salts in the product. Such soluble salts are objectionable in the drilling mud field.
Moreover, barite used for weighting drilling muds should have a specific gravity of 4.20, preferably 4.25 or higher. A specific gravity below 4.20 is sometimes not commercially acceptable.
Accordingly, a flotation process for barite should yield a concentrate rich enough in barium sulfate to achieve the stated minimum of specific gravity. As a result of this consideration, metallurgical recovery in floating barite for oil-well drilling use is a secondary consideration; the primary consideration is the specific gravity of the barite, with the proviso, of course, that metallurgical losses should not be excessive.
Certain mixtures of tall oil fatty acids, sulfo succinamates, mahogany petroleum sulfonates and cetyl sulfate and tallow sulfate, both alkyl sulfates, and salts thereof, have previously been used alone or in admixtures with each other and found to be excellent collecting materials for the froth flotation of barite. These collectors are sufficiently specific in their collecting action for barium sulfate, as well as commercially acceptably removable from the beneficiated mineral at temperatures sufficiently low to prevent excessive formation of soluble salts in the barium product.
At their normally supplied commercial activity, however, these alkyl sulfates and other previously-used collectors are usually pastes at ordinary operating temperatures; thus, they are difficult to disperse in water, especially under winter conditions when the water is cold. Further, as pastes they must be added manually and cannot be metered into the process.
Further, with respect to the previous use of alkyl sulfates as barite collectors, the equivalent weight range is fairly narrow. Unless cetyl alkyl sulfates having a carbon length distribution of approximately 65% by weight C.sub.16 and 35% by weight C.sub.18 or tallow alkyl sulfates having a carbon length distribution of approximately 35% by weight C.sub.16 and 65% by weight C.sub.18 are used either alone or in an admixture, with no other alkyl sulfates being present, the efficiency from using alkyl sulfates as barite collectors in froth flotation falls off drastically.
The present invention overcomes many of the disadvantages of the prior art by providing a composition for enhancing the froth flotation and collection of barite. The compositions of the present invention are at their preferably supplied activity dispersions which are more highly liquid or fluid-like than these paste-like collecting compositions previously used, such as alkyl sulfates. Thus, the compositions of the present invention are advantageously more easily handled than those previously used pastes and can also be automatically metered into the froth flotation process, rather than added manually. These compositions retain their increased fluid-like or liquid properties at ordinary operating temperatures, at elevated operating temperatures and at temperatures down to approximately 40.degree. F.
The active component of the composition of the present invention is acceptably selective to barite and is also acceptably removable from the beneficiated barite. Barite floated with this composition has an acceptable specific gravity and a commercially acceptable level of soluble salts.
Further, a composition containing the active component may serve both as a collector and a frothing agent, whereas many of the previously used collectors require use of a chemically distinct frothing agent.
Significantly, admixture of the active component of the composition of the present invention with previously-used collector pastes achieves admixtures which themselves are compositions falling within the scope of the present invention. At their preferably supplied activity, these admixtures are more highly liquid or fluid-like than the paste-like collecting composition that have been used previously.
Moreover, admixture of the active component of the composition of the present invention with alkyl sulfates, in addition to forming admixtures which at their preferably supplied activity are more highly liquid or fluid-like than the paste-like compositions previously used, also improves the efficiency of alkyl sulfates other than cetyl alkyl sulfates and tallow alkyl sulfates as barite collectors. Accordingly, alkyl sulfates heretofore unacceptable as barite collectors can now be used more efficiently when admixed with the active component of the composition of the present invention. Further, these previously unacceptable alkyl sulfates, when admixed with the active component of the composition of the present invention, can also be admixed with the previously acceptable C.sub.16 -C.sub.18 alkyl sulfates. The resulting admixture, a composition which is an effective frother and barite collector, thus falls within the scope of the present invention.